The present invention may be efficiently implemented in a single VLSI integrated circuit of low cost. The present invention provides for a very high channel count, limited only be the speed and cost of the circuit and the average degree of upward pitch shifting required. Also, the present invention allows for use of multiple interpolator circuits to be used with a single waveform memory.
The present invention relates to electronic musical instruments, and more particularly to digital sampling instruments which create musical notes by reproducing recorded waveforms of musical instruments or sound effects, or mathematically calculated waveforms from a waveform memory at a variable playback rate. As has been previously disclosed in the above-identified cross-referenced patent application Ser. No. 07/462,392 filed Jan. 5, 1990 one technique for improving the performance of such instruments is the use of a cache memory and waveform interpolation. Such a technique increases the available channel count of the instrument by eliminating the waveform memory access time bottleneck which limits performance. While the basic use of cache memory has been previously described, there are several improvements beyond the preferred embodiment described in patent application Ser. No. 07/462,392 which are described herein.